Region free NTSC and PAL

Hi all.

I'm hoping someone can answer this question for me.....

I wish to create a DVD to be played in various regions (PAL & NTSC). I know that in Encore CS5 I can create a Region free (0) DVD but do I need to create a PAL and an NTSC version (Im currently working in PAL)?

OR can I just use 1 version to be played worldwide?

Thanks